Human Embryo/Fetus Development - King's College London Lecture 1 PDF

Faculty of Life Sciences & Medicine 09/2024 Prof Anthony Graham Module Code – 4BBA1010 Module Title – Fundamentals of Anatomy Department of Anatomy Lecture Title – Building a Human ...

Faculty of Life Sciences & Medicine 09/2024 Prof Anthony Graham Module Code – 4BBA1010 Module Title – Fundamentals of Anatomy Department of Anatomy Lecture Title – Building a Human  Faculty of Life Sciences & Medicine 09/2024 Prof Anthony Graham Module Code – 4BBA1010 Module Title – Fundamentals of Anatomy Department of Anatomy Lecture Title – Building a Human  S Building a Human - Key steps in early development Learning objectives: Know the steps of pre- and post-implantation development Understand the process of gastrulation and its importance Understand the significance of the germ layers Understand neurulation and its importance Appreciate the significance of the neural crest Understand what somites are and their importance Understand what endoderm is and know its main derivatives Appreciate that the development of the head is different Understand the growth of the embryo/foetus and the basic anatomy The key events in human development occur at the very earliest stages of embryogenesis Overview of development Week 1 is concerned with the formation of supporting tissues and implantation Cleavage - follows immediately after fertilization. A series of rapid cell divisions , without growth, that divides the embryo into numerous small cells  Cleavage generates the blastocyst - The trophoblast interacts with the uterus, the embryo derives from the inner cell mass. The first phase of embryogenesis is concerned with establishing support for the embryo  The inner cell mass rearranges to form the blastodisc - This consists of two layers - the epiblast and the hypoblast Gastrulation is the process through which cells sort out to generate the body plan. This involves the inward movement of cell from the epiblast The germ layers are established at gastrulation Development proceeds from anterior to posterior Gastrulation results in the establishment of the main body plan Neurulation - the formation of the neural tube Starts anteriorly ceases posteriorly Neurulation defects The neural crest arises early in development and generates A broad range of derivatives The neural crest gives rise to much of the peripheral nervous system, pigments and in the head skeleton  The notochord is severely reduced in mammals But plays important developmental roles. It is lost in childhood but contributes to the centre of the intervertebral discs, the nucleus pulposis  Human embryo ~ 28 days Chick embryo ~1.5 days Somites, blocks of mesoderm are a prominent feature  Mesodermal cells ingress during gastrulation The somites bud from the anterior of the pre-somitic mesoderm as the embryo extends posteriorly  https://www.youtube.com/watch?v=Upja9l0JPgA https://www.youtube.com/watch?v=rO2JoENBOv0 Somitogenesis – bud off from the anterior part of the presomitic mesoderm  Neural crest migration and motor nerves are organised by the internal subdivision of the somites Derivatives of the mesoderm Defects in somitogenesis results in scoliosis The endoderm is the source of much of the viscera  The development of the head is distinct - lack of coelom, somites of reduced importance, central roles for neural crest cells, for ectodermal placodes, for epithelial primordia, The bones of the skull are derived from both neural crest and mesoderm The development of the frontonasal region involves fusion of A number of primordia The development of the secondary palate involves the growth, elevation And fusion of the palatal shelves Human embryo/fetus development weeks 6-26 The key developmental events occur at the very earliest stages